This invention relates to a foundry composition from which foundry moulds or cores are to be formed and to a method of producing a foundry mould or core.
In U.S. Pat. No. 3,925,296, there is disclosed a foundry binder comprising a polyfunctional phenol and a polyisocyanate. The binder is used by mixing the phenol and the isocyanate with foundry sand and then passing an amine catalyst in gaseous form through the mixture to cause the phenol and the isocyanate to react together and bind the sand.
One object of the present invention is to improve the binder disclosed in the aforementioned patent so that a smaller proportion of the improved binder is required to achieve a given core strength. The reduction of the amount of binder used without any consequent loss in core strength has a number of advantages which are well known. A further object of the invention is the provision of a binder which is less expensive to use than are known binders which produce cores having similar properties.